A driver is a golf club used to hit the first stroke from the tee. The tee has a well-defined, fixed configuration through which each golfer must necessarily pass. However, the golfer's game and capabilities evolve over time. As a result, in the vast majority of cases, the same golfer will not hit the ball twice in an identical manner using the same driver from the same tee. Accordingly, variations which are sometimes appreciable occur in the golfer's performance.
To compensate for these differences in performance, the golfer selects, within a set, the driver which appears to him to be the most suitable, taking into account the inclination of the hitting face of the club head in relation to a reference plane delineated by a so-called "angle of loft."
The golfer will prefer the choice of a driver having fairly slight loft if he feels fit and has confidence in his game. In the contrary case, the golfer will look for a driver having fairly pronounced loft, which gives him more confidence since it facilitates the lift of the ball.
Differences in performance also occur among golfers of differing abilities.
Reduced loft is normally prized by good golfers, while greater loft meets the expectations of more ordinary players.
Generally speaking, there is a close correlation between a golfer's performance and his self-confidence. It has been demonstrated that this confidence is enhanced if the club proves stable when addressing the ball, i.e., when the head rests on the ground before the ball is struck. At this precise moment, the golfer positions the club before raising it in order to execute the hitting motion.
It has already been shown that confidence correlates with the surface area of the sweet spot, that is, with the ideal hitting area located on the front face of a club head. Confidence increases in proportion as the surface area of the sweet spot increases, because, in this case, club tolerance is greater. In fact, even if the stroke is not aimed perfectly, the gap between the true and the optimal impact of the ball on the hitting face does not cause the path to deviate a great deal. A golfer lacking confidence or of modest ability will thus choose a head incorporating a large sweet spot.
On the other hand, when the golfer is confident or plays at a high level, he will choose a small sweet spot, in order to facilitate the proper configuration and accuracy of the trajectory, even if, in this case, the tolerance is reduced.
It thus becomes important to be able to choose, from a set of clubs each having a different loft, and in particular from a set of drivers, a club whose stability when addressing the ball and the size of whose sweet spot are proportional to the loft.
However, under present circumstances, there is no set of woods or drivers in which the size of the sweet spot and the stability of the head resting on the ground before impact with the ball are a function of the angle of loft selected.